The use of soluble polymer-supports in catalysis and synthesis /
Three different approaches have bound catalysts or icrofilm Inc. substrates in this study: acid-base chemistry, thermal responsive been developed to recover soluble polymer-property and thermal responsive behavior. Acid-base chemistry was used to recover polymeric acid derivatives. In this case, an...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1998.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=733039411&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | Three different approaches have bound catalysts or icrofilm Inc. substrates in this study: acid-base chemistry, thermal responsive been developed to recover soluble polymer-property and thermal responsive behavior. Acid-base chemistry was used to recover polymeric acid derivatives. In this case, an amphoteric soluble polyacrylic acid (Gantrez)-bound hydrogenation catalyst is soluble and active in water at pH >7.5 and insoluble and inactive below that pH. Such catalysts are recoverable and reusable and have activities that closely resemble those of a low molecular weight analog. An insoluble polymeric acid was also used to simultaneous deprotect and purify BOC-protected amines. This chemistry was shown to be very useful in solution-phase parallel synthesis. In the second approach, catalysts and substrates are bound to poly(N-isopropylacylamide) (PMPAM) that are in solution and active at low temperatures but precipitate and inactive at high temperatures. Recovery of such catalysts can then be accomplished by heating. Such "smart catalysts'' were shown to be active in many reactions such as hydrogenations, allelic substitutions and C-C coupling reactions. In the third case, we used a thermomorphic system that combines attractive features of diphasic and homogeneous catalysis. This chemistry uses a solvent system (90% EtOH/heptane) that changes thermally from diphasic (25 OC) to monophasic (70 OC) and a polymeric ligand that prefers one phase under diphasic conditions. When a substrate (product) is preferentially soluble in the opposite phase, repetitive reactions proceed in excellent synthetic yield with facile catalyst/product separation at the diphasic stage. In this case, we also discussed some preliminary studies for the air-stable Pd catalysts. Such catalysts are modified with tridentate PCP or SCS lights. They showed high activity in Heck type reactions in open air without any deactivation. More importantly, these PCP-Pd or SCS-Pd catalysts can be bound to polymer supports which leads to air-stable and recoverable palladium catalysts. |
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| Item Description: | Vita. "Major Subject: Chemistry". |
| Physical Description: | x, 145 leaves : illustrations ; 28 cm. |
| Bibliography: | Includes bibliographical references (leaves 134-144). |